This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are interested in testing the reproducibility and detection of hydrophillic peptides by LC-MS/MS using an HPLC system with and without a trapping column. Trapping columns are typically used in nanoLC systems because they allow for more rapid sample loading. However, during loading, the more hydrophillic peptides may be washed off the trapping column. We are interested in determining the degree of peptides that are lost when using a trapping column versus without.